Corrientes, Argentina
Corrientes, Argentina

The National University of the Northeast is an Argentine national university. It is located in the cities of Corrientes and Resistencia, capitals cities of the Provinces of Corrientes and Chaco respectively, and was established on December 4, 1956. Known as the university of the sun, it is the seventh-largest university in Argentina by student enrollment numbers. Wikipedia.

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Lobayan R.M.,Northeast National University
Chemical Physics Letters | Year: 2013

We present a theoretical description of the case of the strained [1.1.1]propellane system by application of the local and nonlocal topological formalisms to the density decomposition into its effectively paired and unpaired contributions. The analysis is mainly focused on the nature of its carbon-carbon headbridge sequence and the existence of 2e-3c complex patterns of bonding. The results clearly indicate that the system only possess 2e-2c patterns, including a true carbon-carbon headbridge bond and no 3c-2e complex patterns of bonding appear. © 2012 Elsevier B.V. All rights reserved.

Cardozo O.D.,Northeast National University | Garcia-Palomares J.C.,Complutense University of Madrid | Gutierrez J.,Complutense University of Madrid
Applied Geography | Year: 2012

In recent years, station-level ridership forecasting models have been developed based on Geographic Information Systems (GIS) and multiple regression analysis. These models estimate the number of passengers boarding at each station as a function of the station characteristics and the areas that they serve. These models have considerable advantages over the traditional four-step model, including simplicity of use, easy interpretation of results, immediate response and low cost. Nevertheless, the models usually use traditional ordinary least squares (OLS) multiple regression, which assume parametric stability. This study proposes a direct model that uses geographically weighted regression (GWR) to forecast boarding at the Madrid Metro stations. Here, the results obtained using the OLS and GWR models are compared. The GWR model results in a better fit than the traditional one. In addition, the information supplied by the GWR model regarding the spatial variation of elasticities and their statistical significance provides more realistic and useful results. © 2012 Elsevier Ltd.

Candia O.A.,Mount Sinai School of Medicine | Mathias R.,State University of New York at Stony Brook | Gerometta R.,Northeast National University
Investigative Ophthalmology and Visual Science | Year: 2012

PURPOSE. In 1997, a theoretical model was developed that predicted the existence of an internal, Na{thorn}-driven fluid circulation from the poles to the equator of the lens. In the present work, we demonstrate with a novel system that fluid movement can be measured across the polar and equatorial surface areas of isolated cow lenses. We have also determined the effects of ouabain and reduced bath [Na+]. METHODS. Lenses were isolated in a chamber with three compartments separated by two thin O-rings. Each compartment, anterior (A), equatorial (E), and posterior (P), was connected to a vertical capillary graduated in 0.25 μL. Capillary levels were read every 15 minutes. The protocols consisted of 2 hours in either open circuit or short circuit. The effects of ouabain and low-Na{thorn} solutions were determined under open circuit. RESULTS. In 21 experiments, the E capillary increased at a mean rate of 0.060 μL/min while the A and P levels decreased at rates of 0.044 and 0.037 μL/min, respectively, closely accounting for the increase in E. The first-hour flows under short circuit were approximately 40% larger than those in open-circuit conditions. The first-hour flows were always larger than those during the second hour. Preincubation of lenses with either ouabain or low-[Na{thorn}] solutions resulted in reduced rates of fluid transport. When KCl was used to replace NaCl, a transitory stimulation of fluid transport occurred. CONCLUSIONS. These experiments support that a fluid circulation consistent with the 1997 model is physiologically active. © 2012 The Association for Research in Vision and Ophthalmology, Inc.

Pays J.-F.,Northeast National University
Bulletin de la Societe de Pathologie Exotique | Year: 2011

Infection of carriers of strongyloides by the human oncogenic retrovirus HTLV-1 significantly augments the number of larval parasites in the stools and impairs the action of anti-helminthic agents, resulting in an increase in immediate and longer term failure of therapy. The proliferation of cytokine type 1 secreting lymphocytes, the preferred target for viral infection, shifts the Th1/Th2 balance in favour of a Th1 response with a consequent increase in the production of gamma interferon (INF-γ). In addition to other effects, this causes a decrease in the secretion of cytokines IL-4, IL-5 and IL-13, which results in substantial reduction in total and specific IgE; failure of activation of eosinophils or stagnation in or reduction of their numbers; and an increased risk of development of a severe form of strongyloidiasis. This risk is clearly correlated with the level of anti-HTLV-1 antibodies and the amplitude of the proviral load of peripheral lymphocytes. The polyclonal expansion of infected CD4 cells might be partly due to the activation of the IL-2/IL-2R system by parasite antigens together with the action of the virus type 1 Tax protein. The fact that adult T cell leukaemia arises significantly earlier and more often in individuals with combined infection is an argument in favour of the parasite's role as a leukaemogenic co-factor. In practice it is, therefore, appropriate to initiate all available measures to eliminate parasites from co-infected hosts although this does present difficulties, and one should not reject the possibility of a diagnosis of strongyloidiasis in the absence of hypereosinophilia. In all cases of chronic strongyloidiasis without hypereosinophilia, co-infection with HTLV-1 should be looked for routinely. The same applies to carriers of strongyloides with repeated treatment failures. Finally, corticosteroids and immunosuppressants should be used only with care in HTLV-1-positive patients who seem not to be co-infected, even if they have received precautionary therapy. © Société de pathologie exotique et Springer-Verlag France 2011.

Canteros M.G.,Northeast National University
Drug Discovery Today | Year: 2014

In humans, as in other mammals, endogenous glucocorticoids (GCs) are essential for adapting to physiological life stress. They are also crucial for the healthy development of the fetus. However, when the physiological concentrations of GCs increase over a long period of time, the central nervous system (CNS) is predisposed to the development of psychiatric disorders and neurological diseases. Here, I discuss the strong influence of GCs on the nitric oxide (NO) pathway and the generation of reactive oxygen species (ROS). I also highlight supporting evidence for the neuroprotective actions of d-arginine (d-Arg) against neurotoxicity induced by high levels of GCs in the CNS. Given that d-Arg does not interfere with the immunosuppressive and anti-inflammatory effects of GCs, this might be a novel way of neutralizing the neurotoxic effects of GCs in the CNS without compromising their positive peripheral actions. © 2013 Elsevier Ltd.

Mroginski J.L.,Northeast National University | Etse G.,National University of Tucuman
Computers and Geotechnics | Year: 2013

In this paper a new finite element formulation for numerical analysis of diffused and localized failure behavior of saturated and partially saturated gradient poroplastic materials is proposed. The new finite element includes interpolation functions of first order (C1) for the internal variables field while classical C0 interpolation functions for the kinematic fields and pore pressure. This finite element formulation is compatible with a thermodynamically consistent gradient poroplastic theory previously proposed by the authors. In this material theory the internal variables are the only ones of non-local character. To verify the numerical efficiency of the proposed finite element formulation, the non-local gradient poroplastic constitutive theory is combined with the modified Cam Clay model for partially saturated continua. Thereby, the volumetric strain of the solid skeleton and the plastic porosity are the internal variables of the constitutive theory. The numerical results in this paper demonstrate the capabilities of the proposed finite element formulation to capture diffuse and localized failure modes of boundary value problems of porous media, depending on the acting confining pressure and on the material saturation degree. © 2012 Elsevier Ltd.

Hojsgaard D.H.,Northeast National University | Hojsgaard D.H.,University of Gottingen | Martinez E.J.,Northeast National University | Quarin C.L.,Northeast National University
New Phytologist | Year: 2013

Meiotic and apomictic reproductive pathways develop simultaneously in facultative aposporous species, and compete to form a seed as a final goal. This developmental competition was evaluated in tetraploid genotypes of Paspalum malacophyllum in order to understand the low level of sexuality in facultative apomictic populations. Cyto-embryology on ovules, flow cytometry on seeds and progeny tests by DNA fingerprinting were used to measure the relative incidence of each meiotic or apomictic pathway along four different stages of the plant's life cycle, namely the beginning and end of gametogenesis, seed formation and adult offspring. A high variation in the frequencies of sexual and apomictic pathways occurred at the first two stages. A trend of radical decline in realized sexuality was then observed. Sexual and apomictic seeds were produced, but the efficiency of the sexual pathway dropped drastically, and exclusively clonal offspring remained. Both reproductive pathways are unstable at the beginning of development, and only the apomictic one remains functional. Key factors reducing sexuality are the faster growth and parthenogenetic development in the aposporous pathway, and an (epi)genetically negative background related to the extensive gene de-regulation pattern responsible for apomixis. The effects of inbreeding depression during post-fertilization development may further decrease the frequency of effective sexuality. © 2012 New Phytologist Trust.

Mroginski J.L.,Northeast National University | Etse G.,National University of Tucuman
International Journal of Solids and Structures | Year: 2014

In this work, analytical and numerical solutions of the condition for discontinuous bifurcation of thermodynamically consistent gradient-based poroplastic materials are obtained and evaluated. The main aim is the analysis of the potentials for localized failure modes in the form of discontinuous bifurcation in partially saturated gradient-based poroplastic materials as well as the dependence of these potentials on the current hydraulic and stress conditions. Also the main differences with the localization conditions of the related local theory for poroplastic materials are evaluated to perfectly understand the regularization capabilities of the non-local gradient-based one. Firstly, the condition for discontinuous bifurcation is formulated from wave propagation analyses in poroplastic media. The material formulation employed in this work for the spectral properties evaluation of the discontinuous bifurcation condition is the thermodynamically consistent, gradient-based modified Cam Clay model for partially saturated porous media previously proposed by the authors. The main and novel feature of this constitutive theory is the inclusion of a gradient internal length of the porous phase which, together with the characteristic length of the solid skeleton, comprehensively defined the non-local characteristics of the represented porous material. After presenting the fundamental equations of the thermodynamically consistent gradient based poroplastic constitutive model, the analytical expressions of the critical hardening/softening modulus for discontinuous bifurcation under both drained and undrained conditions are obtained. As a particular case, the related local constitutive model is also evaluated from the discontinuous bifurcation condition stand point. Then, the localization analysis of the thermodynamically consistent non-local and local poroplastic Cam Clay theories is performed. The results demonstrate, on the one hand and related to the local poroplastic material, the decisive role of the pore pressure and of the volumetric non-associativity degree on the location of the transition point between ductile and brittle failure regimes in the stress space. On the other hand, the results demonstrate as well the regularization capabilities of the non-local gradient-based poroplastic theory, with exception of a particular stress condition which is also evaluated in this work. Finally, it is also shown that, due to dependence of the characteristic lengths for the pore and skeleton phases on the hydraulic and stress conditions, the non-local theory is able to reproduce the strong reduction of failure diffusion that takes place under both, low confinement and low pore pressure of partially saturated porous materials, without loosing, however, the ellipticity of the related differential equations. © 2014 Elsevier Ltd. All rights reserved.

Vitreorana uranoscopa inhabits small or medium-sized streams with rocky bottoms of the Interior Atlantic Forest of eastern Brazil, northeastern Argentina, and likely southeastern Paraguay. Most of the available information originates from Brazilian populations. Only a few populations from Argentina have been reported and information about their natural history is almost unknown. This work re-describes the advertisement call of V. uranoscopa from a new population discovered in the province of Misiones, Argentina, and includes further data about its reproduction, population density and habitat conservation status. On the basis of 11 recorded males, two call types were recorded. Results showed that the typical advertisement call is formed by pulsed notes released singly, in groups, or in combinations of both at an average rate of 13.86 notes/min. Notes lasted 0.013-0.085 s and had 1-5 well-defined pulses lasting 0.003-0.015 s; the pulse repetition rate was 90.9-166.66 pulses/s. The peak of dominant frequency was 4,312.5-4,875.0 Hz with a slight, ascending frequency modulation. These data agree with those reported in previous studies, although some differences in the note duration, intercall interval, number of pulses and harmonics were identified. These differences might be due to either the technological limitations at the time of those studies or interpopulation variation. The second call type (reported for the first time in V. uranoscopa) is formed by 1-2 additional pulses at the beginning of some notes and has lower amplitude than typical calls, but the social context of its emission is still unknown. The calling males perched on the leaves of the marginal vegetation, either alone or occasionally in groups of 2-3 individuals, with a average of 5.5 individuals per 100 m transect. Clutches containing up to 36 eggs or embryos were found on the upper surface of fern fronds. In Argentina, V. uranoscopa occurs only in Araucaria forests of the Interior Atlantic Forest. Thus, the protection of streams with abundant marginal vegetation seems to be essential for the conservation of this species. © 2014 Brazilian Society of Herpetology.

A new species of a fossil crustacean clam shrimp (Spinicaudata: Eosestheriidae) Menucoestheria wichmanni is described from the lower Upper Triassic Vera Formation (Los Menucos Complex) in Rio Negro Province, southern Argentina. This discovery represents the first record of this family in the Triassic of Argentina and the southernmost record of South American Triassic 'conchostracans' (Spinicaudata). The new species shows close affinities with Middle Jurassic faunas from Antarctica and offers important data on the taxonomy (notably the use of ornamentation characters), palaeobiogeography (as South America hosts the oldest-known fossils of this family) and evolution of the Gondwanan faunas. Other South American eosestheriid species are tentatively recognized. Menucoestheria is hypothesized to be the ancestral form of the Triassic-Jurassic Gondwanan eosestheriids. Relationships between European and Gondwanan eosestheriids remain unresolved. © 2010 Association of Australasian Palaeontologists.

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